1. Field of the Invention
The invention generally relates to a yarn carrier, and more specifically, to a yarn carrier for feeding a yarn to the needles of a circular knitting machine which minimizes needle wear, and which is easier for an operator to thread.
2. Description of the Prior Art
Circular knitting operations generally utilize one or more circles of needles which knit one or more yarns sequentially to form a continuous tube of fabric. In order to produce a flawless fabric, the manner in which the yarn(s) are fed to the needles must be performed in a precise manner. Present-day circular knitting machines generally utilize a plurality of yarn feeds and operate at high speeds to produce fabrics at high rates of production. However, the speeds at which a machine can be run are generally limited by such factors as the rate at which yarn can be accurately fed to the needles, the rate of needle motion, and the speed with which the needle latches can be accurately opened and closed.
In conventional circular knitting machines, the yarn carrier feeds the yarn to the knitting machine where the cylinder needles intersect with the dial needles or with the sinkers. It is important that the yarn carrier be properly positioned to provide satisfactory yarn feeding to the needles, in order for the knitting operation to proceed smoothly, without interruption, and without the formation of fabric defects. Desirably, the yarn carrier feeds the yarn such that it is readily received by each of the needle hooks, which dictates that the carrier is positioned in extremely close proximity to the circle of needles. However, this close positioning can sometimes result in the needle hooks and/or needle latches having a tendency to enter the opening in the yarn carrier through which the yarn being fed extends. This can cause the needles to become broken or damaged, which can in turn lead to fabric defects and production stoppages. Furthermore, adjustments to the yarn carrier are often required for variations in yarn tension, the tightness of the stitches being knit, tuck stitch formation, and for tuck and welt patterning.
One approach for improving the feeding of yarns to the needles of a knitting machine is described in U.S. Pat. No. 4,441,339 to Yorisue. That patent describes a two piece yarn carrier construction having a yarn guide with a yarn feed aperture and a guard plate overlapping the yarn guide and interposed between the yarn guide and the latch needles. These plates, of which the inventor of the instant invention is a manufacturer and distributor, are customarily made of a thin sheet of metal. These guard plates have been found to perform well in the prevention of premature needle closure and in the prevention of entry of the needle hooks and latches into the yarn feeding aperture of the yarn guide.
One problem which has been encountered with the devices described in the '339 patent, however, is that when an operator attempts to set up the knitting machine by threading each of the yarn guides with their respective yarns, the guard plate tends to interfere with the insertion of the yarn through the yarn guide aperture. Consequently, many operators have a tendency to grab the free end of the guard plate and bend it away from the yarn guide during the threading process. Because the guard plates are made from metal, they often retain a somewhat bent position when the operator releases the free end. This bend can become even more pronounced upon subsequent threading operations. As a result, the guard plate often retains a position in which it extends outwardly from the yarn guide, where it can interfere with the proper motion of the needle latches and yarn feeding. Consequently, fabric defects and even needle smashes can be caused through the improper positioning of the guard plate and its interference with the knitting operation. As should be apparent, interference with proper knitting function can have an extremely negative impact on production efficiency and fabric quality.
Another problem encountered with these prior art yarn carriers is that the guard plate tends to undesirably wear the needle latches and hooks as a result of frictional contact between the needle latches and the guard plate. This can result in a reduction in the life span of the needles, as well as needle damage, which can in turn lead to fabric defects. Similarly, the friction between the needles and the guard plate can have an adverse effect on the guard plate.